Package designers for power semiconductor devices are faced with numerous mutually-exclusive goals, necessitating a balance between performance, flexibility, manufacturability, reliability and cost of the final product. One elusive parameter to quantify for a new package development is the total project cost incurred for engineering and transferring a robust, high yielding design to a volume manufacturing environment. A true total cost calculation is further complicated when materials, process development and assembly equipment aspects are factored into the equation. A thorough performance assessment and reliability appraisal are also documented to establish that all design goals have been achieved.
The aforementioned considerations become increasingly difficult to manage in radio frequency, microwave, and optical applications in which high power levels and harsh environments make it difficult to devise a consistent methodology with which to characterize all electrical, mechanical and thermal attributes of package integrity. In such applications, there is a need to maximize design re-use of processes and materials which have previously been qualified for functionality and purpose.
The designer of semiconductor packaging has available a wide array of previously established materials and principles upon which to build. Applications are generally narrow enough in scope that designers are afforded flexibility to mitigate performance, cost and reliability concerns. However, as the product of operating power and operating frequency becomes increasingly large, the options available to the package designer diminish greatly, and as a consequence the number of different packages or packaging technologies required for such applications tends to specialize and proliferate, with a resulting drain on resources and escalating costs.